import pygame
class Ship():
	def __init__(self, ai_settings, screen):
		"""初始化飞船并设置气初始位置"""
		self.screen = screen
		self.ai_settings = ai_settings
		#加载飞船图像并获取其外接矩形
		self.image = pygame.image.load("images/ship.bmp")
		self.rect = self.image.get_rect()
		self.screen_rect = self.screen.get_rect()
		#将每艘新飞船放在屏幕底部中央
		self.rect.centerx = self.screen_rect.centerx
		self.rect.bottom = self.screen_rect.bottom
		self.center = float(self.rect.centerx)
		self.moving_right = False
		self.moving_left = False
	def update(self):
		if self.moving_right and self.rect.right < self.screen_rect.right:
			self.center += self.ai_settings.ship_speed_factor
		if self.moving_left and self.rect.left > 0:
			self.center -= self.ai_settings.ship_speed_factor
		self.rect.centerx = self.center
	def blitme(self):
		"""在指定位置绘制飞船"""
		self.screen.blit(self.image, self.rect)
